1. Field of the Invention
The invention relates to an abrasive material, to a method for its manufacture and to the use of this abrasive.
2. Description of the Prior Art
The abrasion of profiles is frequently carried out with endless abrasive belts which must be guided via an abrasive contact wheel, a drive roll, if necessary a reversal roll and a tension roll, etc.
In order that the abrasive belt can be adapted to the contours of the workpiece to be processed, it is pressed from the rear side against the workpiece to be abraided by means of a rigid profiled abrasion shoe or abrasion block. A further possibility consists in that the workpiece is abraided by means of the abrasion contact wheel, the latter also being provided with the counterprofile of the workpiece to be processed.
Other devices for the abrasion of profiles using coated abrasives consist of profiled abrasion blocks, abrasion shoes, abrasion contact wheels or abrasion wheels which are overlaid by means of a flexible coated abrasive, for example using glueing or welding. In order to ensure adaption of the abrasive to the profile, it was previously necessary mostly to use expensive methods such as for example the cutting or provision of upset grooves.
In each case the requirement exists that the flexible abrasive is adapted exactly to the contours of the given profile.
In German Offenlegungsschrift No. 30 36 991 a device is mentioned for abrasion, particularly for surface abrasion of wooden parts, which consists in that an abrasive body is used which consists of an elastic raw material and which is surrounded at least partially by an endless abrasive belt which is elastic. Preferably the belt joint region of the abrasive belt is formed elastically.
In European Patent Application No. 0 052 866 A3, an abrasive belt for profile polishing is described which consists of an extensible fabric backing coated with abrasive particles, the warp threads of which backing running at a sharp angle of 20.degree. to 60.degree. to the belt direction and the abrasive belt having longitudinal zones of low extensibility.
It is true that some earlier known flexible coated abrasives had a certain degree of extensibility. This extensibility was however insufficient to satisfy the requirements which for example are made upon an abrasive for profile grinding. Even the abrasive on the fabric backing in which the extensibility was increased according to EP No. 0 052 866 A3, proves to be insufficient with difficult profiles. With the use of such an extensible abrasive, the breaking off of the abrasive particles is also very problematical as soon as it is stretched or extended more than a certain extent; such a degree of stretching is often required in profile polishing.
In the already mentioned German Offenlegungsschrift No. 30 36 991 it is explained that the manufacture of an elastic abrasive band (with the previously known abrasive) would not be possible owing to the disturbance of the surface during extension and the resulting breaking off of the abrasive particles.